Diesel engines continue to be all the rage in Europe while they're just beginning to gain ground again in the U.S. As proof that diesels aren't just considered high-mileage motors for city cars, we offer up these spy shots of the BMW 635d, a version of the 6-Series that will be rocking the automaker's twin-turbo 3.0L diesel engine. The motor in the 635d should produce about 286 hp and 428 ft-lbs. of torque. Motor Authority expects a 0-60 time of about six seconds combined with what will likely be the best fuel consumption of any 6-Series model.

These spy shots show a slightly updated 6-Series model with a revised front bumper, but we know there's a diesel underhood because the spy photographer managed to get a pic of the car's gauges, which show the word "diesel" above the fuel gauge.

Along with the TT 3.0L diesel, the 6-Series is also expected to replace the 630i's engine with the award-winning twin-turbo 3.0L inline six from the the 3-Series. While we may see the new 635i in the U.S. soon enough (currently only the V8 650i is offered), the way things are going we don't expect the 635d to make the trip over anytime soon.

[Source: Motor Authority]